Police detection speed cameras known in the art employ a dedicated laser transmitter/receiver, coupled to a camera located in the same body or casing, which is used to acquire images of the vehicle the speed of which is being measured by the laser assembly. Speed measurement is accurately derived by computing the time difference between laser light emitted by the laser gun, and reflected laser light returning to it from the target vehicle.
In order to provide evidence of the speed at which the vehicle was traveling at the time of measurement, a camera acquires an image of the vehicle (which typically, in modern laser guns is done in digital form), which permits to identify it. In prior art laser guns the camera typically consists of a different module assembled on the laser gun body. FIG. 1 schematically shows three prior art architectures of laser guns of this type. In all cases the image-acquiring element (camera) 1 is mounted on the casing of the laser transmitter/receiver, either above or below it. The camera needs to be aligned to the laser gun transmitter since it is located in a different location on the laser gun body and needs alignment to the laser beam so that the acquired image coincides with the vehicle, the speed of which is being measured. However, because of that structure (as illustrated in FIG. 1) prior art laser guns may become easily misaligned. For instance, if the camera module suffers an impact (e.g., by being dropped, or hit while leaving the car, or thrown on the back seat, etc.) its calibration is altered, which may result in the image of the wrong vehicle being taken or, in other words, the vehicle the speed of which is being measured may not be the same vehicle portrayed in the photograph taken at the time of measurement. This problem has caused many issues in legal proceedings against speeding drivers, making it difficult to convince the courts that the measured speed that was attributed to a given driver was actually that of the car in the photograph.
It is therefore clear that it would be highly desirable to provide a laser speed gun that does not suffer from the aforementioned problems, and which is reliable in both measuring speed and in matching that measurement to the correct vehicle.